Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 281855

Area Forecast Discussion
National Weather Service Wilmington NC
255 PM EDT Tue Mar 28 2017

Showers and an isolated strong thunderstorm remain possible
this afternoon ahead of a cold front which will move through
late tonight. Relatively cooler and drier high pressure will
build in from the north late Wednesday into Thursday. Showers
and thunderstorms are expected as warmer and more humid air
returns Friday ahead of a cold front which will move offshore
early Saturday. Some of the thunderstorms may be strong to
severe Friday and Friday night. The weekend should be dry as
high pressure takes hold. Then early next week, a southern
stream system will again bring the risk for showers and


As of 3 PM Tuesday...A second shortwave is crossing the Carolinas
this afternoon and with the early shortwave there has been a delay
in additional convection developing. The GOES-16 1-minute imagery is
showing cumulus developing west of Florence to Pembroke and isolated
cumulus developing to the west. The 16 UTC HRRR is only showing
isolated convection through sunset. So will keep a 20 to 30% chance
of convection with the higher chances for the northern coastal

The frontal boundary will shift across the area after midnight and
sweep to the south with high pressure building in the area into
Wednesday. Lows tonight are expected to fall into the upper 50s and
highs on Wednesday to around 80 except cooler at the beaches with a
northeast flow.


As of 3 PM Tuesday...Mid level ridge axis over the southeast will be
deamplifying and shifting east Wed night as surface high over
southern Canada builds down the east coast. Cooler air associated
with the Canadian high spreads over the region Wed night with lows
dropping close to climo. Northeast winds will be in the 5 to 8 mph
range which should prevent any radiational cooling. Low will be in
the low to mid 50s across much of the area. Surface high shifts off
the coast later Thu with weak return flow developing Thu night.
Ridging aloft Wed night and Thu will keep the region dry through at
least Thu evening. Forecast soundings show impressive subsidence
from 850mb through 700mb into Thu night before approaching high
amplitude southern stream system shunts the 5h ridge axis
farther off the coast.

Developing deep southwest flow Thu night increases moisture in
the region, precipitable water values increase from around 0.80"
Thu evening to 1.40" by the end of the period. Arrival of this
deeper moisture along with an increase in mid level lapse rates
should open the door for some convection late in the period. The
unfavorable timing and lack of strong low level jetting does
suggest coverage will be rather limited and do not plan on much
in the way of changes to inherited Thu night precip chances.
Temperatures Thu will be near to slightly below climo, upper 60s
to lower 70s, with temps Thu night running above to well above
climo and likely following an atypical curve with slight warming
after midnight.


As of 300 AM Tuesday...Next in series of potent southern stream
systems will impact the eastern Carolinas Fri and Fri night with
a categorical risk for showers and thunderstorms developing.
The combination of significant upper level support and strong
and deep moisture return and lift provides at least the
opportunity for a more widespread and significant rainfall
event. There will be some risk for strong to severe
thunderstorms during this time. 0-6 km effective bulk shear
parameters are not particularly impressive. However, instability
does grow with mixed layer CAPE values on the order of 500 to
1000 J/kg as the warm front should move to our N. Mid-level
lapse rates are forecast to be rather modest. The potential is
there for an active day/night leading into the weekend, although
magnitude is certainly still a question mark.

In the wake of this system, dry weather and near to above
normal temps are expected for the weekend as mid-level ridging
builds across the area and surface high pressure builds from the
NW and N. Attention then will turn westward as next southern
stream system along the Gulf Coast Sun night lifts to the NE and
drags a warm front to the N. This will again bring deep
moisture into the Carolinas, and with that, showers and
thunderstorms early next week. Given timing differences between
long range models and a general slower trend as compared to 24
hours ago, will cap POPs in the chance category until we can
gain better resolution as to when the highest risk for showers
and thunderstorms will occur.


As of 18Z...The first batch of convection has shifted off the
coast. The TAF sites are now VFR but with a second shortwave
crossing the area by late afternoon there is a chance of
convection developing and some of these thunderstorms may
contain hail and gusty winds. At this time with the coverage
being generally less than 30% will include VCTS for KFLO, KILM,
and KLBT. Chances are slightly less for KCRE and KMYR.

Southwest winds are expected to veer to the the northwest and
north with a cold frontal passage after 06 UTC. VFR conditions
are expected after 06 UTC.

Extended outlook...Flight restrictions are likely
in showers and thunderstorms Fri/Fri night and thunderstorms may
contain strong wind gusts. VFR conditions are expected Saturday
and Sunday.


As of 3 PM Tuesday...SW winds around 15 knots with higher gust are
seen at coastal CMAN stations...not receiving any offshore buoy data
at this minute so have lower confidence of the current wind speeds
at 10 to 20 miles off the coast.  With cold front approaching expect
to see winds increase to 15 to 20 knots with higher gust. Seas are
expected to peak at 3 to 5 feet. Will continue to see longer period
swells through this evening. With the cold frontal passage expected
between 2 AM and 6 AM Wednesday, seas will slowly fall to the 3 to 4
feet range by the end of Wednesday.

As of 3 PM Tuesday...Northeast flow will continue Wed night and
Thu as high pressure over southern Canada builds south.
Gradient becomes pinched late Wed night as cold surge moves
across the waters and northeast flow may briefly hit 20 kt.
Northeast flow remains 15 to 20 kt Thu before starting to
decrease and veer to east Thu evening and then southeast Thu
night as the surface ridge axis moves offshore. Seas will range
from 3 to 5 ft through Thu night with shorter wave periods
expected given the strength of the northeast flow. Exercise
caution headlines may be needed during the period, depending on
the strength of the northeast surge late Wed night.

As of 300 AM Tuesday...A Small Craft Advisory is likely for all
waters Fri and Fri night with conditions possibly lingering
into Sat.

Slow moving area of low pressure will be moving across the Ohio
Valley Fri. Its accompanying warm front will move across the
waters Fri. As low pressure moves offshore of the Mid-Atlantic
states late Fri night and Sat morning, it will strengthen and
drag a cold front across the waters. High pressure will slowly
build across the area from the N and NW Sat night and Sun.

SE winds Fri morning will become S and then SW Fri night. The
wind direction will become westerly early Sat morning and then
NW by Sat afternoon. N winds Sat night will become NE overnight
Sat with NE winds persisting into Sun before veering to easterly
during the afternoon.

The strongest winds are expected Fri and Fri night, up to 20 to
25 kt. Seas late Fri and Fri night will build to 4 to 7 ft and
around 8 ft at frying Pan Shoals. Seas during Sat will only slowly
subside as backswell from departing storm system impacts the
waters. Seas should drop below advisory levels by late Sat and
to 2 to 4 ft on Sun.





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